import java.util.Scanner;

public class Test19092304 {
	public static void main(String[] args) {
		Scanner scanner=new Scanner(System.in);
		int n,m,a;
		n=scanner.nextInt();
		m=scanner.nextInt();
		a=scanner.nextInt();
		double d =(n/a);
		double s =(m/a);
		System.out.println(d*s);
	}

}
